Ocular herpes simplex virus (HSV) infections are one of the leading infectious causes of human blindness in the U.S. Despite extensive research on the subject, it remains unclear why certain individuals are predisposed to the frequent recurrence of herpetic lesions. Recent evidence indicates that antigen or mitogen - activated human lymphocytes, but not resting lymphocytes, will support HSV replication. A loss of the immune function of HSV replicating lymphocytes was demonstrated. This investigation will address itself to the question of whether or not various populations of peripheral blood lymphocytes (PBL) from patients with recurrent herpetic corneal lesions can support HSV replication after stimulation with HSV antigen. If so we will (1) compare patient and control lymphocytes for possible differences in the population(s) that is susceptible to HSV replication; (2) determine the effect of HSV replication in cultures of lymphocytes on the level of cytotoxic activity in these cultures; (3) determine the effect of HSV replication in cultures of various populations of lymphocytes on the ability of these cells to elaborate soluble factors which can augment or suppress the cytotoxic activity of natural killer cells and cytotoxic T lymphocytes. HSV replicating lymphocytes will be detected by the virus plaque assay. Cytotoxic activity will be measured by a 51Cr-release assay.